The HPT will log a lot more stuff than an ELM interface. I think it talks on the CAN bus
There was some stuff I had to enable / disable to get rid of the learn-down after I installed my turbo kit, trying to remember what it was. Even with the tune from the kit vendor there were some tweaks necessary.
Still, 19-20PSI is pretty awesome.
I assume you know the thing about switching the traction control / stability control modes?
(Sorry, I'm sure you've researched all this to death.)
Oh, here's my fun development from a couple of weeks ago:
It took a year to get that bumper.
11 months and 23 days, to be more precise. Looking for a GXP bumper as I really don't want to wait another year for this one.